Black-clad anarchists on Sunday stormed into what had been a largely peaceful Berkeley protest against hate and attacked at least four people, including the leader of a politically conservative group who canceled an event a day earlier in San Francisco because of fears violence could break out.

The group of more than 100 hooded protesters, with shields emblazoned with the words "no hate" and waving a flag identifying themselves as anarchist , busted through police lines, avoiding security checks by officers to take away possible weapons. Then the anarchists and blended in with a crowd of 2,000 largely peaceful protesters who turned up to demonstrate in a "Rally Against Hate" opposed to a much smaller gathering of right-wing protesters.

Among those assaulted by the anarchists was Joey Gibson, the leader of the Patriot Prayer group, who canceled a rally Friday and was prevented from holding a news conference on Saturday when authorities closed off the public square Gibson planned to use. Gibson has said he launched Patriot Prayer after several supporters of President Donald Trump were beaten at a Trump campaign stop in San Jose, California last year.

After the anarchists spotted Gibson at the Berkeley park, they pepper-sprayed him and chased him out of it as he backed away with his hands held in the air, accompanied by a masked man wearing football shoulder pads. Gibson and the man went behind a line of police wearing riot gear, who set off a smoke bomb to drive away the anarchists.

Earlier in the day, another group of left-wing demonstrators dressed in black attacked at least three men in the park, kicking and punching them until the assaults were stopped by police. Police also used a smoke grenade to stop one scuffle.

Police in the San Francisco area have been braced for violence and trying to prevent protests that draw left-wing and right-wing opponents since the deadly confrontation in Charlottesville, Virginia, on Aug. 12 during a rally of white supremacists.

Berkeley authorities did not issue a permit Sunday's gathering of right-wing protesters and Berkeley Mayor Jesse Arreguin had urged counter-protesters to stay away.

It had been canceled by organizer Amber Cummings, who encouraged supporters to stay away but said she would attend on her own.

By mid-afternoon Cummings had not appeared and left-wing protesters far outnumbered right-wing supporters.

Earlier in the day, police had set up barricades around park and checked people who entered to make sure they did not have prohibited items like baseball bats, dogs, skateboards and scarves or bandanas they could use to cover their faces.

Several people were arrested for violating rules against covering their faces or carrying items banned by authorities.

"You are an immigrant," said Karla Fonseca. "You should be ashamed of yourself."

Several other people also yelled at the man, who said he was born in Mexico but supports Trump's proposal to build a wall along the southern border.

Police pulled one supporter of President Donald Trump out of the park over a wall by his shirt as a crowd of about two dozen counter demonstrators surrounded him and chanted "Nazi go home" and pushed him toward the edge of the park. At least two people were detained by officers for wearing bandannas covering their faces.

A separate group of counter protesters had assembled earlier Sunday at the nearby University of California, Berkeley campus and then marched park to merge with the anti-rally protesters who had already gathered there.

Both Cummings and Gibson have disavowed racism and say they wanted to hold the rallies to bring conservative voices to the liberal San Francisco Bay Area.

Student activism was born during the 1960s free-speech movement at Berkeley, when thousands of students at the university mobilized to demand that the school drop its ban on political activism.

However, the violence in Charlottesville led San Francisco area police and civil leaders to rethink their response to protests.